Ever higher performances in skiing make ever greater demands on skiing equipment, especially on ski boots. Above all, measures should be taken which reduce the stressing of the feet and legs of the skier in order largely to avoid fatigue phenomena which are frequently the cause of fractures.
On the other hand, these measures should render it possible for the skier to exert greater influence upon the skis. To realise these requirements, stiffer and higher ski boots are designed which, while they permit the skier to exert considerable influence upon the ski, also involve the danger of fractures of the tibia and fibula and what are called boot-upper edge fractures. Especially in deep-snow skiing, modern skiing techniques often require extreme relieving of the forward ski parts. In order to achieve this, the ski boots are built with even higher uppers. Apart from the fact that thus the calf muscles are constrained, the mobility of the tibia and fibula is greatly limited. The designers of ski boots are in a dilemma because, on the one hand, the ski boot should be of rigid formation in order to transmit the forces better to the ski, and on the other hand, it should be flexible enough to permit anatomically natural movement of the legs.